Typewriter: hack in support for not committing text changes until the timer fires. It's done in a way that seems to play well with undo/redo

git-svn-id: http://svn.gna.org/svn/etoile/trunk/Etoile/Frameworks/CoreObject@10554 7b3f36aa-e6db-49c1-8b4c-66eac1997e64